title: Phonatory characteristics of the excised human larynx in comparison to other species.
abstract: OBJECTIVE
  The purpose of this study was to determine the conditions needed to elicit phonation from excised human larynges and the resultant range of phonations produced; compare that with similar information previously obtained from canine, pig, sheep, and cow; and relate those findings to previously reported information about viscoelastic properties of the vocal fold tissue (ie, stress-strain curves and Young's modulus).
  
  
  METHODS
  Six human larynges of the geriatric group (age range, 70-89) were mounted on the bench without supraglottic structures, and phonation was achieved with the flow of heated and humidified air through the tracheal tube. Using various sutures to mimic the function of the laryngeal muscles, the larynges were put through a series of sustained oscillations with adduction as a control parameter.
  
  
  RESULTS
  The human larynges oscillated with an average frequency that was close to the canine larynges, but the oscillation behavior and wide frequency range were similar to those of pig larynges. The similarity of the wide vibration frequency ranges of human and pig larynges may be because of the nonlinear behavior of their elasticity, which is related to the high collagen content of the vocal folds. On the contrary, other species with limited frequency ranges showed almost linear stress-strain curves because of the higher elastin and lower collagen contents.
  
  
  CONCLUSIONS
  The physiological differences in the linearity and ranges of oscillation of excised larynges reported in this study and previous studies are reflective of the tissue composition and mechanics.
authors.affiliation: Department of Communication Sciences & Disorders, The University of Iowa, Iowa City, Iowa 52242, USA. alipour@iowa.uiowa.edu
authors.forename: Fariborz
authors.initials: F
authors.lastname: Alipour
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Finnegan
authors.forename: Sanyukta
authors.initials: S
authors.lastname: Jaiswal
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D004285:Dogs; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D007825:Laryngectomy; D007830:Larynx / Q000502:physiology* / Q000601:surgery; D008297:Male; D017711:Nonlinear Dynamics; D009991:Oscillometry; D010699:Phonation; D011312:Pressure; D012756:Sheep; D013045:Species Specificity; D013314:Stress, Mechanical; D013552:Swine; D014732:Vibration